Vending machines used to dispensed candy and snack products are adapted to offer a very large selection of products from a single machine. Each of the products being offered is dispensed by a single dispensing device including a spiral shaped coil or auger driven by an electrically operated gear motor. The snack products are positioned linearly between the coils of the auger and the gear motor rotates the augur, usually through a single 360 degree rotation, to dispense a single product. The wiring for the gear motors that drive the various augurs are arranged in rows and columns and a controller applies power through a multiplex circuit to drive the motor for dispensing the product that a customer has selected. Once the customer has selected a product, the controller applies power to the appropriate motor by closing switches to the wires for the correct column and row of the motor operating the auger. The gear motor and augur continue to rotate through a cycle (which may be 360 degrees) after which the augur returns to its home position. A cam on the output shaft of the gear motor operates a switch creating an electric signal to the electronic controller after which the controller terminates power to the gear motor causing it to stop in the home position.
A vending machine for dispensing snack products and candy may have fifty or more independently operated gear motors for dispensing products. The electronics for the vending machine therefore must include a sensor for sensing when the shafts for each of the fifty or more rotatable shafts has reached its respective home position. Although the metal parts of a vending machine are useable for a ground, existing vending machines employ at least one wire directed to each of the gear motors to provide the needed feedback to the controller for terminating power to the gear motors after they have completed rotation through 360 a cycle. It should be appreciated that most products are dispensed with the gear motor rotating through a 360 degree cycle, but some products may require less than a full rotation and other products may require more than full rotation of the shaft. Where the machine employs a large number of gear motors, the wire harness complexity increases. It would be desirable, therefore, to provide an improved method of controlling the gear motors of a vending machine such that each gear motor of the machine will provide a signal to the controller when the associated rotatable shaft has returned to its home position, without requiring a wire attached to each of the individual motors.